Color vision is something that many of us are able to take for granted, though the perception of color may have a significant bearing on a patient’s ocular health. While the majority of our patients have normal color vision, color vision can be affected by congenital or acquired eye diseases.
Humans typically have 3 different ‘cones,’ or color-sensing cells in the retina. These different cells are each most sensitive to a specific wavelength of light, or color. When a person is born without one of the three color-sensing cone-types, they will have sub-optimal color perception (often called, rather incorrectly, a ‘color blindness’). The most common color anomaly is deuteranomaly, which is caused by a reduction or complete lack of the green-sensing cones in the back of the eye. Males are most susceptible to this disorder because the gene for this type of color deficiency is located on the X chromosome. Because females have 2 X chromosomes, they can have one faulty chromosome (making them a ‘carrier’) and one normal chromosome. In that scenario, their color vision would be normal. Males, on the other hand, have a single X chromosome and if they have a faulty X-chromosome, they will be color deficient.
It is best for a patient to know if they have a color issue early in life so that they can plan their career accordingly. While a color perception-impaired individual will have some difficulties distinguishing certain colors, there are only a few occupations that would exclude them because of it. Electricians, airline pilots, and some military jobs require normal color vision. Unfortunately, tinted lenses will not restore normal color vision as the root problem is a lack of a specific type of color-sensing cells in the retina. Treatment with stem cells is showing some promising results, though at this time, there is no way to correct color perception in an individual with a color-sensing problem.
While most color perception difficulties are congenital, color vision can also be affected during one’s lifetime by a variety of eye diseases. Optic neuropathy, retinitis pigmentosa, macular degeneration, glaucoma, Stargardt disease, and chloroquine retinopathy can all alter one’s color vision. For this reason, it is important to establish a solid baseline color test for our patients’ medical records.
At Vista Eye Care in Thornton, Colorado, our eye doctors may test color vision two different ways. We perform a color vision screener for all our new patients as part of our comprehensive eye and vision examination. Our screening books determine only if you are color normal, or if you potentially have a color perception difficulty. If our screening book suggests a color perception issue, we will test the patient with a highly specific test to determine the type of color deficiency (protanope, deuteranope) and the depth of the impairment (mild, moderate, or deep). This information is important so that the patient can plan their career choice according. While we recommend children have their first eye and vision exam before 1 year of age, we don’t start testing children’s ability to perceive color until they are about 4-5 years of age. At that age they are better able to reliably share their subjective responses.
We test color vision as a baseline on all our new patients. Call our office today to schedule your yearly comprehensive eye and vision examination.